Icebreakers could be built faster and with less expense. Instead of breaking the ice with a ship's hull an ice crusher assembly can be used. A new icebreaker can be built or an existing ship can be modified. The speed of breaking the ice could increase as well. The Coast Guard's heavy polar icebreakers are capable of continuous progress through ice 6 feet thick at a speed of 3 knots, for ice at 21 feet an icebreaker has to use the backing and ramming technique. This is very hard on the icebreaker's hull and engines, perhaps the crew as well.